Elasmobranch scanner tech ready for War on Terror

The US Navy's plan to detect mines and other underwater objects by their electrical fields - in the same way as sharks and rays find prey - has moved closer to reality.

Elasmobranch fish (rays, sharks and suchlike critters) have various senses, including relatively conventional vision and smell. But they also have slime-filled "canals" in their heads known as "the ampullae of Lorenzini," after the Florentine court doctor who documented them in 1678. (In seventeenth-century Florence, the ducal physician was apparently expected to dissect any sharks that happened to turn up.)

The slime tubules, it later turned out, are effectively biological voltmeters with sensitivities as fine as a few microvolts. Sharks use them to detect the bioelectric fields of bottom-feeding flatfish lying concealed in sand or mud, so as to scoff them.

Normally, when the US Navy figures out that a marine lifeform has a useful ability, they simply sign a few creatures up on a fish-based remuneration package. The USN has a large force of dolphin and sea lion mercenaries on its books, and in the past has experimented with killer whales, pilot whales and even trained seagulls. Apparently, "trainability assessments" were carried out on sharks too; but it seems that USN handlers never really felt comfortable working with them. Jaws just isn't as nice as Flipper, apparently. For whatever reason, there are no sharks on the Navy payroll today, though there are - of course - plans afoot to use them as remote control brain-chipped zombie slaves.

Meanwhile the USN was envious of the sharks' amazing sensing abilities, for all that these seem to be quite limited. Experiments indicate (pdf) that a shark needs to pass within 15cm of a hidden flatfish in order to pick it up on slime-scan. Of course, circuitry in a sea mine could provide a stronger signal than bottom-feeders' bioelectricity, but on the face of it the shark's abilities aren't that impressive.

Nonetheless, in 2005 the Navy signed up three separate companies to pursue shark-in-a-box style sensor tech which could be used in coastal waters where conventional sonar tends to struggle.

"The shark operates in this difficult environment with great success," said the Navy boffins, no doubt having viewed Jaws a few times.

They were looking for a piece of kit no bigger than three feet long and 4.75 inches in diameter which could be used by Navy divers underwater. It was specified that under Phases I and II of the project "two or three prototypes" would be developed. Phase III approval would mean that "this system will have immediate use in surveillance and monitoring operations with Homeland Security, Global War on Terrorism, Joint Forces Operations, and future combat systems."

"QUASAR Federal Systems, Inc. of San Diego is being awarded a $6,000,000 ... Phase III contract for ... 'Shark Weak Electromagnetic (EM) Field Detection for Moving Objects.' The objective is to develop a covert/low-observable sensor system for detecting and classifying small, slow moving surface or subsurface bodies in coastal shallow water, bays, port areas, or waterways utilizing weak EM signals or field deviations. This technology has broad applications for both DoD and other Defense agencies. Work ... is expected to be completed in June 2012."

So there we have it. Pork handouts have enabled the building of prototype shark-in-box gear, and we ought to see it at sea from 2012.